Sensor arrangement having sensor array provided on upper portion of a container

ABSTRACT

A chemical sensing system has: an interrogation unit operable to wirelessly transmit an interrogation signal and wirelessly receive a response; an environmentally sealed container for holding a chemical analyte; a sensor array unit in fluid communication with the analyte disposed within the container, where the sensor array unit is operable to generate a response in the presence of a chemical stimulus; and a passive responder unit connected with the sensor array unit, the responder unit being powered from the interrogation signal, where the responder unit is operable to wirelessly receive the interrogation signal and wirelessly transmit the response to the interrogation signal to the interrogation unit.

The present invention is a continuation of U.S. application Ser. No.11/365,938, filed Mar. 2, 2006 now U.S. Pat. No. 7,201,035, which itselfis a divisional of U.S. application Ser. No. 10/864,551, filed Jun. 10,2004 now U.S. Pat. No. 7,040,139, which claims priority to U.S.Provisional Application Ser. No. 60/477,624, filed Jun. 10, 2003, theentire contents of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to a sensor arrangement andtechniques for the detection of analytes. More specifically, the presentinvention relates to electronic techniques and devices for olfactiontype detection/analysis, where the sensor arrangement is wirelesslyconnected to the processing arrangement which processes the output ofthe sensor arrangement, and therefore allows the sensor arrangement behermetically isolated from the processors and/or remotely disposed withrespect to the same.

2. Related Art

Techniques and devices for detecting a wide variety of analytes influids such as vapors, gases and liquids are known. An “electronic nose”is an instrument used to detect vapors or chemical analytes in gases,solutions, and solids. In certain instances, the electronic nose is usedto simulate a mammalian olfactory system. In general, an electronic noseis a system having an array of sensors that are used in conjunction withpattern-recognition algorithms. Using the combination of chemicalsensors, which produce a fingerprint of the vapor or gas, therecognition algorithms can identify and/or quantify the analytes ofinterest. The electronic nose is thus capable of recognizing unknownchemical analytes, odors, and vapors.

In practice, an electronic nose is presented with a substance such as anodor or vapor, and the sensor converts the input of the substance into aresponse, such as an electrical response. The response is then comparedto known responses that have been stored previously. By comparing theunique chemical signature of an unknown substance to “signatures” ofknown substances, the unknown analyte can be determined. A variety ofsensors can be used in electronic noses that respond to various classesof gases and odors.

A wide variety of commercial applications are available for electronicnoses including, but not limited to, environmental toxicology andremediation, biomedicine, such as microorganism classification ordetection, material quality control, food and agricultural productsmonitoring, heavy industrial manufacturing, ambient air monitoring,worker protection, emissions control, and product quality testing. Manyof these applications require a portable device because they are locatedin the field or because they are inaccessible with respect to largerlaboratory models.

While handheld electronic nose devices are commercially available, theygenerally require the device to be in close proximity with the analyte.In certain circumstances, where the analyte is potentially a hazardouscompound, the requirement of close proximity can potentially expose theoperator of such a device to hazardous conditions. While it may bedesirable to break up the sensing array subunit from the processingsubunit, such an option is difficult to implement, primarily due to thepower requirements of the sensor array unit, as well as the need tomaintain a direct electrical connection between the sensor array and theremainder of the sensing device.

On the other hand, in an unrelated area of industry, remote, so called“passive” identification has flourished. An implementation of passiveidentification technology includes radio-frequency tags. Radio-frequency(“RF”) tags have been used by industry for many years. Common usesinclude identification of rail cars, automobiles, cattle management andsalmon returning to spawn in the Columbia River, as well as embeddingthe tiny tags under the skin of a pet to identify a lost dog or cat.Many people encounter RF tags when a store clerk removes theft-deterringdevices from expensive clothing items.

RF and other passive tags have enabled a method of identifying itemsfrom a distance, commonly called RFID, or radio frequencyidentification. RIFD systems generally comprise two components, namelytransponders which are attached to the items to be labeled, and readersfor reading the identity of the transponders. In some cases thetransponders might be programmed to broadcast data representing theiridentity, while in other cases, it might be an ON/OFF state such as isused in electronic article surveillance systems commonly used foranti-shoplifting in retail stores. RFID systems use small tags thatcontain information about the object to which the tag is attached. Inits simplest form, a radio-frequency tag is a small electronic circuitboard. It contains a suitable antenna and/or coil. The tags store data,such as the identification number correlating to an item. The tag beinga passive device does not require a battery. A device called aninterrogator or a reader is used to read the tags. The interrogatorincludes another electronic circuit, typically larger than the tag, thatcontains an antenna and a transceiver. The antenna emits radio waveswhich are received by the RF tag, and which is energized thereby. Thetag transmits its stored, encoded data back to the interrogator whereinit is decoded.

While RFID technology and electronic article surveillance have seen manyadvances, the tag technology has generally been limited to rathersimplistic arrangements which merely issue prestored data in response toan interrogation signal sent by an interrogation unit.

There is, therefore, a need to extend RFID technology to include moreintelligent arrangements such as a versatile robust chemical sensingsystem for obtaining information pertaining to an analyte (e.g.presence, concentration, etc.) in various diverse testsamples/environments via a wireless/remote query, without requiring ahardwired connection between the sensing elements and the dataprocessing arrangement.

A BRIEF SUMMARY OF THE INVENTION

The present invention uses these two unrelated technology areas toprovide a passive chemical sensor system where the sensing unit iswirelessly/remotely located from the processing unit and where thesensing unit does not require its own self-contained power source.

More specifically, a first aspect of the invention resides in a sensorarrangement, comprising: an interrogation unit operable to wirelesslytransmit an interrogation signal and to wirelessly receive a response; acontainer configured to be environmentally sealed and for holding achemical analyte; a sensor unit in fluid communication with the analytedisposed within the container, the sensor unit being configured torespond to the analyte; and a responder unit connected with the sensorunit, the responder unit and the sensor unit being respectively poweredby the interrogation signal, the responder unit being operable towirelessly transmit to the interrogation unit a signal indicative of thesensor unit's response to the analyte.

In the above arrangement the responder unit comprises an antennaconfigured to respond to the interrogation signal to produce anelectrical signal that enables the responder unit and the sensor unit.Thus, the responder unit is a passive arrangement. It can include anintegrated circuit. The sensor array unit and the passive responder unitmay be combined in a single integrated circuit.

Preferably, the response which is generated by the sensor unit is ameasurable electrical property such as a voltage or can take the form ofan electromagnetic signal. The interrogation unit or interrogator, as itwill be sometimes referred to, preferably includes a transceiver and canbe a handheld device.

The above mentioned sensor unit comprises a plurality of sensors whichform a sensor array wherein each sensor in the sensor array is a memberselected from the group consisting of a bulk conducting polymer film, asemiconducting polymer sensor, a surface acoustic wave device, a fiberoptic micromirror, a quartz crystal microbalance, aconducting/nonconducting regions sensor, a dye impregnated polymericcoatings on optical fiber or combinations thereof. Preferably, theresponder unit further includes one of a transmitter and a transceiver,and the interrogation unit can further comprises processing circuitrywhich processes the response received by the interrogation unit toidentify the analyte.

Preferably, the interrogation unit can include a device for receiving aninput from an operator, and a device for providing an output to anoperator. In given embodiments, the interrogation unit and the sensorarray unit are inductively coupled. Alternatively, the interrogationunit and the sensor array unit may be capacitively coupled.

A further aspect of the invention resides in a sensing method,comprising: placing a sample comprising an analyte in a container;closing the container and enclosing a sensor array therein; exposing thesensor array to the sample; using an interrogation unit to wirelesslytransmit an interrogation signal to a responder unit operativelyconnected with the sensor array; powering the responder unit and thesensor array unit, using the interrogation signal; generating a responseindicative of the analyte as sensed by the sensor array; and wirelesslytransmitting the response to the interrogation unit using the responderunit. Alternatively, the sample may be suspected of containing ananalyte or a threshold amount thereof.

In this method, exposing the sensor array to the analyte allows sensorelements of the sensor array to react to the analyte. Further, the stepof locating the sensor array in the container is such that it is exposedto a gaseous medium in the container.

Preferably, the above-mentioned method includes processing thewirelessly transmitted response from the responder unit, to identify theanalyte. In this case the step of generating the response can includegenerating a measurable electrical property.

A further aspect of the invention resides in a sensor arrangementcomprising: a container configured to receive a sample and to be closedto retain the sample therein; a sensor arrangement disposed within thecontainer and configured to be exposed to a gaseous medium in thecontainer which gaseous medium contains an analyte which has apredetermined relationship with a sample introduced into the container;and an antenna and transmitter arrangement disposed within thecontainer, the antenna being configured to be responsive to anelectromagnetic signal generated externally of the container to producesufficient electrical energy to activate the sensor array and atransmitter coupled to the sensor array and to induce the emission of asignal indicative of the analyte in gaseous medium as sensed by thesensor array.

Preferably, the above arrangement further includes an interrogatorconfigured to wirelessly communicate with the sensor arrangement and towirelessly excite the sensor arrangement to emit the signal indicativeof the analyte. The interrogator and may be portable and may behandheld.

The above mentioned interrogator, in addition to being portable, can beconfigured to store the emitted signal indicative of the analyte, andcan be configured to display the nature of the analyte upon it beingdetermined. The interrogator may be configured to wirelessly relay to aremote host device the data contained in the emitted signal indicativeof the analyte. Further, the interrogator can be also configured to scanan external surface of the container and derive data relating to thecontainer and/or its contents.

Yet another aspect of the invention resides in a sensor arrangementcomprising: a sensor device configured to be exposed to an analyte in agaseous medium; and an antenna and a transmitter arrangement operativelyconnected with the sensor device, wherein the antenna is configured tobe responsive to a wirelessly transmitted interrogation signal toproduce sufficient electrical energy to activate the sensor device andthe transmitter coupled to the sensor arrangement and to induce theemission of a signal indicative of an analyte as sensed by the sensordevice.

In accordance with this aspect of the invention, at least the sensorarrangement is configured to be disposed in a container, and thecontainer is configured to retain a sample in a manner wherein thesensor is exposed to a space in the container in which the gaseousmedium collects. The vapor in the space comprises the gaseous mediumwhich comprises the analyte.

In addition, the interrogation signal is produced by an interrogatordevice which is configured to receive and decipher the signal indicativeof the analyte as sensed by the sensor array. The interrogator devicecan be configured to relay to a host device data contained in the signalindicative of the analyte as sensed by the sensor array. Thecommunication between the interrogator and the host is a wirelesscommunication.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the exemplary embodiments of theinvention will be derived from the following detailed description takenin conjunction with the accompanying drawings wherein:

FIG. 1 is a block diagram which schematically depicts a wireless,passive chemical sensor system in accordance with an embodiment of thepresent invention.

FIG. 2 is a block diagram of a method of sensing an analyte inaccordance with another embodiment of the present invention.

FIG. 3 is a schematic depiction of a hand-held interrogator extractinginformation from a sensor arrangement which is enclosed in a containerin which an sample has been disposed and wherein the sensor arrangementhas been exposed to the vapors emitted from the sample.

FIG. 4 is a view similar to the that shown in FIG. 3, but wherein datawhich has been transmitted to the interrogator from the sensorarrangement is subsequently relayed to a host device such as a mainframe or the like type of device capable of interpreting/collating datawhich has been gleaned from the sensor.

FIG. 5 is a view showing an interrogator collecting data such as from abar code or the like via the use of an optional optical reader which canbe collated with the data derived from the sensor arrangement within thecontainer.

FIG. 6 is a block diagram which schematically depicts a wireless,passive chemical sensor system in accordance with another embodiment ofthe present invention.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

In general, the embodiments of the present invention relate to achemical sensing system using sensing devices that are wirelesslyconnected with the associated pick-up/receiver and processing units thatare used for chemical analyte sensing and monitoring.

More particularly, the invention relates to a novel wirelessly connectedarrangement that has sensing elements that respond to an analyte oranalytes.

This novel sensing structure may be used to sense the presence,concentration, or absence of chemical elements and compounds (whetheruseful or unwanted/contaminating in a liquid, gas, or plasma state), pHlevels, germs (bacteria, virus, etc.), enzymes, antibodies, and so on ina number of environments such as biomedical applications (whether invivo or in vitro), within medical test samples, food quality/inspection(whether measuring moisture within sealed packing or outside ofpackaging), monitoring of heavy metals found in water (groundwater,treated water, or wastewater flowing in natural waterways, canals, orpipes), and monitoring of solid or gas manufacturing waste, etc. Thisnew, versatile sensing apparatus and method marries the techniques ofradio frequency based identification with those of chemical sensorarrays, such as those used for artificial olfactometry.

FIG. 1 schematically depicts a passive, wireless chemical sensor systemin accordance with an embodiment of the present invention. It will beunderstood that the term “passive” is used in this disclosure to referto an arrangement which needs to be activated from a “slumbering” orinactive state via the wireless transmission of an interrogation signalthereto. This system comprises an interrogation unit 10 and a samplingunit 20. The sampling unit 20, in this embodiment, includes a sealablecontainer 22 that is used to hold a sample including an unknown analytethat is to be identified by the chemical sensor. A sensor or sensorarray 24 is in fluid communication with an interior space of thecontainer 22. This communication while being normally a constantcommunication is not limited thereto and it is within the scope of atleast one embodiment of the invention to arrange this communication tobe selectively interruptible if so desired.

Each sensor in the sensor array unit may include a conducting polymerfilm, a semiconducting polymer sensor, a surface acoustic wave device, afiber optic micromirror, a quartz crystal microbalance, aconducting/nonconducting regions sensor, a dye impregnated polymericcoatings on optical fiber and/or combinations thereof.

In an exemplary embodiment, the sensor array, consists of a plurality ofindividual thin-film carbon-black/polymer composite so called“chemiresistors” which are configured so as to besimultaneously/serially exposed to the analyte. The sensor array 24 isused to generate an output (which comprises a plurality signals fromeach of the chemiresistors) when exposed to an analyte. This output isused to identify the analyte using a data analysis technique such asthat which uses data analysis algorithms.

These chemiresistors include a composite material of conductive carbonblack homogeneously blended throughout a nonconducting polymer. Thedetector materials are deposited as thin films on an alumina substrateand are each provided with two electrical leads to create a conductingchemiresistor.

When the composite material is exposed to a vapor-phase analyte, thepolymer matrix acts like a sponge and “swells up” while absorbing theanalyte. The increase in volume is concomitant with an increase inresistance because the conductive carbon-black pathways through thematerial are broken. When the analyte is expelled, the polymer “sponge”off-gasses and “dries out”. This causes the film to shrink and theconductive pathways are reestablished. The baseline resistance(Rbaseline) of the device is measured while a representative backgroundvapor is exposed to the array. The response from the chemiresistorduring an analyte exposure is measured as a bulk relative resistancechange (Rmax/Rbaseline). Since an analyte will absorb into the differentpolymer matrices to different degrees, a pattern of response is observedacross the array.

The polymer matrix “swells up” because analyte vapor absorbs into thefilm to an extent determined by the partition coefficient of theanalyte. The partition coefficient defines the equilibrium distributionof an analyte between the vapor phase and the condensed phase at aspecified temperature. This is expressed as:K=Cs/Cvwhere Cv is the concentration of the analyte in the vapor phase, and Csis the concentration of the analyte in the condensed phase, which isalso proportional to the detector's response. Therefore, the larger ananalyte's partition coefficient, the more it will absorb into a polymerfilm, and the larger will be the detector's response.

Each individual detector element requires a minimum absorbed amount ofanalyte (Cs,min) to cause a response noticeable above the baselinenoise. However, the minimum vapor concentration (Cv,min) needed toproduce Cs,min is different for each analyte since the partitioncoefficient is different for each analyte. Moreover, it can be shownwith standard thermodynamic arguments, that the magnitude of response ofan individual detector can be predicted to first order by the fractionalvapor pressure exposed to the detector irrespective of the analyteidentity. Therefore, the general detection limit of a sorption device isbest expressed as a minimum fraction of equilibrium vapor pressurerather than a concentration value.

This behavior explains why sorption devices are rather insensitive, interms of concentration, to high vapor pressure analytes like methane(which is a gas at ambient temperatures) and diethyl ether, but showgood sensitivity, in terms of concentration, to low vapor pressurecompounds exposed at low concentrations such as volatile fatty acids.For example, if the limit of detection were 0.1% of an analyte's vaporpressure, this would indicate a detection limit of 74 ppm for ethanol,but only 0.5 ppm for nonanal (a common taint in packaging materials) at24° C. All analytes will have roughly the same limit of detection whenexpressed as a fractional vapor pressure.

The differences between detector responses when exposed to a givenanalyte—which are required to uniquely identify that analyte byproviding a unique response pattern—are due to differences in chemicalinteractions between the analyte and the detector films. Therefore, thelimit of discrimination between two analytes exposed at the samefractional vapor pressure is determined by their relative collectivechemical differences across the array. Generally, chemical diversityshould be very high in the polymers comprising the array detectors for ageneral-purpose electronic nose. Moreover, for well-definedapplications, the polymers used in the detector array can be chosen tomaximize chemical differences between target analytes to increase thediscrimination power of a smaller array.

The composite sensor technology as implemented by the embodiments of thepresent invention are very effective in identifying analytes, becausethey are not reliant on any particular polymer type or limited to aparticular set of polymers. Additionally, the simplicity of signaltransduction (merely reading resistance values) and the low materialscost of the detectors (composites made of carbon black and genericpolymers) makes this an ideal technology for a low-cost, hand-held,electronic nose.

The sensor array 24 is coupled with a transceiver 26. The sensor array24 and the transceiver 26 functions in a manner similar to atransponder, in that the sensor array is normally off until thetransceiver 26 receives an interrogation signal transmitted by theinterrogation unit 10. The sampling unit 20 is coupled to theinterrogation unit 10, whereby the sensor output data from the sensor 24is supplied to the interrogation unit 10. As will be described below,data is transmitted from the sampling (or sensing) unit 20 to theinterrogation unit 10. The interrogation unit 10 receives the sensoroutput data from the sensing unit 20 and either processes the dataitself, stores it locally for later downloading, or transmits the datato another unit for further processing.

The sampling or the sensing unit 20 via the transceiver 26 is able tocommunicate with the interrogation unit 10 through the use of a wirelessdata transmission technique such as a radio frequency signal. With thisapproach, wireless, contactless reading of the chemical sensor array 24is accomplished. Such communication provides one important advantage ofthis embodiment of the present invention, since the reading of thechemical sensor array is accomplished by minimizing/eliminating contactbetween the operator and the analyte.

For example, once the sensor array response is transmitted to theinterrogation unit, the sealed container holding the analyte can besafely disposed of and/or placed in storage for further reference.

In the arrangement illustrated in FIG. 1, the interrogation unit 10includes, merely by way of example, a transceiver 18 which is coupled toa processing subunit 16. The processing unit 16 receives the sensoroutput signals and processes it to determine the identity of theanalyte. The interrogation unit 10 also includes input and outputsubunits 14 that are used to communicate information to the user of theinterrogation unit. In one embodiment, the interrogation unit 10 is ahandheld device.

The sensing unit may be powered by the interrogation signal issued bythe interrogation unit 10. Thus, the sensing unit 20 does not require abattery or other form of self-contained power source. Because no batteryis needed, the sensing unit 20 may be stored and used requiring littleor no maintenance.

Further details of the sensor array, its methods of manufacture as wellas the processing of its output by the processing unit are provided inU.S. Pat. No. 6,495,892, entitled: “Techniques and Systems for AnalyteDetection”; U.S. Patent Application Publication No. US 2002/0098119 A1,entitled: “Electronic Techniques for Analyte Detection,” and U.S. Pat.No. 6,422,061, entitled: “Apparatus, Systems and Methods for Detectingand Transmitting Sensory Data Over a Computer Network,” the disclosuresof which are hereby incorporated by reference herein their entirety forall purposes.

In operation, the interrogation unit 10 transmits a signal wirelessly tothe sensing unit 20. The signal is received by an antenna which convertsthe signal into an electrical signal. This electrical signal is used topower up the transceiver and to pass a small current through each of theresistor elements (chemiresistors) which comprise the sensor array. Thetransceiver can include a microchip which memorizes the voltage signalsoutput by the sensor elements of the sensor array and stores them readyfor transmission to the interrogation unit 10.

Once the interrogation unit 10 has received a data transmission from thesensing unit 20, the interrogation unit may do all the necessaryprocessing locally, or it may in turn transmit the sensor output data onto a further device, such as a host computer for further processing.Once the interrogation signal ceases to be received by the antenna ofthe sensor unit 20, the sensing unit returns to its normally off orpowered down state.

In a second embodiment as shown in FIG. 6, the sensing unit 20 includesa power supply system 610 including a storage device 620 to storeelectrical power generated by the receipt of the interrogation signaland thus enable the sensing unit to continue functioning even in theabsence of the interrogation signal.

The sampling or sensing unit 20 and the interrogation unit 10 may becoupled together either inductively or capacitively. With inductivecoupling, the sensing unit is powered by the electromagnetic fieldgenerated by the interrogation unit. The sensing unit's antenna picks upthe electromagnetic energy to communicate with the interrogation unit.The sensing unit modulates the electromagnetic field in order togenerate and transmit the sensor array data back to the interrogatorunit. The data is processed by the interrogation unit or sent to anotherdevice or a host computer for further processing. In inductively coupledunits, a metal coil made of copper or aluminum wire is wound into acircular pattern and is connected with the transceiver 26. The coil alsoacts as the sensing unit's antenna.

Capacitively coupled units are able to reduce the cost of the system, bydoing away with the metal coil and use a small amount of silicon toperform the same function as the inductively coupled units. In acapacitively coupled unit, by using an electrically conductive inkinstead of metal coil, a cost reduction is realized. Capacitivelycoupled units are also powered by the electromagnetic field generated bythe interrogation unit.

The interrogation and the sensing units may also be coupled usingvarious different industrially available standards. These include:acoustic magnetic, electromagnetic, medium RF, and microwave. Theacoustic magnetic coupling is based on the principles that by exciting astrip of amorphous magnetic material that is also mechanically stressed,with a low frequency magnetic field, the strip will emit harmonics ofthe scanning or interrogating signal, allowing the harmonics to bedetected and hence provide a detection and sensing system. In theelectromagnetic coupling, the sensing unit includes a magnetic materialwhich is illuminated by a pulse of energy, and the decay of theenergizing field is monitored by the interrogation unit. In medium RFcoupling, the sensing unit comprises a tuned circuit that is tuned tothe frequency of the scanning system, typically between 6 MHz and 10MHz. The interrogator unit's transceiving antenna is made by printingconductive circuitry on either side of a plastic film, andinterconnecting the two surfaces. The sensing unit's circuit resonatesat the interrogating frequency when in the presence of the interrogator.With microwave coupling, the interrogator and the sensing unit arecoupled via microwave radiation.

In addition to medium RF coupling, other RF coupling means are alsosuitable for coupling the interrogator and the sensing unit. These RFcoupling technologies include low frequency and high frequencycouplings. Using low frequency, the sensor unit and the interrogatorcommunicate with one another using frequencies in the kHz range (e.g.,125 kHz, 134.2 kHz, and so on). The advantage of using low frequencytechnology is that it will result in a less expensive system, howeverthe system will tend to have a shorter effective range. Using highfrequency, the sensor unit and the interrogator communicate with oneanother using frequencies in the MHz to GHz range (e.g., 13.56 MHz, 400MHz, 2.5 GHz, 5.8 GHz, and so on). The advantage of using a highfrequency design is that the system will have a longer range, but willtend to be more expensive. Yet alternately, the interrogation unit andthe sensor unit can communicate over the combined low and UHFfrequencies (e.g., 134.2 kHz to 903 MHz, and so on).

Various embodiments use RF coupling to link the interrogator and thesensing system, as it relates to either unit's transceiver coil orantenna design. In FIG. 1, the sensing unit 20 is illustrated incommunication with the interrogator 10. The interrogator 10 includes atransceiver 18 and an antenna circuit 19 that emits electromagneticwaves that are used to provide an interrogating field to the sensingunit 20. The antenna circuit 19 includes, in the illustratedarrangement, an inductor 191, a capacitor 192 and a resistor 193. Theresistor 193 may further include a variable resistor.

The sensing unit 10 further includes an antennal circuit 29 whichincludes an inductor 201 and a capacitor 202. The interrogating fieldprovided by the interrogator 10 induces a current in the inductor 201which charges the capacitor 202 that is used to provide power to thesensing unit 20. After being powered up, the sensing unit's sensor arraygenerates an output in response to being exposed to the analyte andtransmits the sensor array data via the antenna circuit 29 to theinterrogator 10. The sensor unit 20 and the interrogator unit may bothinclude a memory circuit for the storage of information derived usingthe sensor array output.

In the arrangement illustrated in FIG. 1, the antenna arrangements aredual purpose antenna, wherein the same antenna is used to send theinterrogation signal and receive the sensor output. The advantage of adual purpose antenna is that it tends to be lower in cost and allows fora more compact overall size. The disadvantage of a dual purpose antennais that it tends to have a shorter range and have a limited impedancematching.

Accordingly, in an alternate embodiment, the transceiver uses a dualantenna, where different receive and transmit antennas are used. A dualantenna embodiment allows for a longer range, but tends to be moreexpensive and somewhat larger. Suitable shapes for the transmivreceiveantennas include conductive coils, spirals, elongated wires and cables,and so on. The interrogation unit's field generating antenna establishesan alternating electromagnetic field of desired frequency and amplitudein the environment surrounding the sensing unit or at least the sensingunit's antenna. The amplitude of the field necessary to generate apredetermined signal level (sensor amplitude response) will varydepending upon system parameters such as coil size, electriccharacteristics of the resonant circuit, and sensitivity of receivingelectronics in the interrogation and sensing units.

Furthermore, the specific type of antenna used to detect emissions fromany one, or several, of the sensor units will depend upon (among otherthings) the type of emission being received, the distance the emissionstravel, and physical design of the receiving antenna. For example, asensing apparatus designed for detecting electromagnetic emissionconsidered in the low frequency range (up to about 20 MHz) must bepaired with a suitable electromagnetic pick-up coil located up to akilometer from the sensing structure; whereas, if the emissions musttravel a much greater distance (several kilometers—such as that from asatellite), the equipment preferably must be capable of operation athigher frequencies (above 20 MHz to the 80 GHz range). Antennatechnology for designing an electromagnetic send/pick-up antennasuitable for use and capable of operating up to 80 GHz is readilyavailable.

FIG. 2 is a block diagram 300 depicting a method of sensing an analytein accordance with an embodiment of the present invention. First, asample containing an unknown analyte is placed in a container (step302). The container is then sealed, such as for example, by placing acap on the container (step 304). The container's cap includes theremainder of the sensing unit 10 described in FIG. 1 above. Once thecontainer is sealed, the sensor array is exposed to the analyte (step306) either by diffusion, convection and/or by movement of the sealedcontainer. Next, the interrogator is used to wirelessly transmit asignal to the sensing unit (step 308). Next, the signal is received bythe sensing unit's antenna. The received signal (1) powers up thesensing unit; (2) causes the sensor array to generate an output signalcorresponding to the analyte; and (3) causes the sensing unit'stransceiver to wirelessly transmit the sensor array output signal backto the interrogation unit. The sensor array output signal is received bythe interrogation unit (step 310) and then the interrogation unitprocesses the sensor signal to identify the analyte (step 312).

In addition to the embodiments described above, other embodimentswherein the interrogation unit wirelessly communicates with the sensorelement/array/unit in the sensing system provide features as follows:

(a) The sensing unit may be used for one-time (e.g., disposable)operation, or periodic operation.

(b) The system may be used for operation within a wide range of testingenvironments such as biomedical applications (whether in vivo or invitro), within medical test samples, food quality/inspection (within oroutside of sealed packing), monitoring of contaminants in water(groundwater, treated water, or wastewater flowing in natural waterways,canals, or pipes), and monitoring of gases/aerosols. The sensingstructure can be driven by having the current be induced in the sensingstructure by an electromagnetic field(s) generated using a remote coilin the interrogator.

(c) Several sensing units may be incorporated into an array to provide apackage of sensing information about an analyte, such as, analytecomposition, and the concentration of constituent components/elements ofthe analyte in which the analyte(s) is found.

(d) A unit having the capacity to generate an interrogation field, asneeded, as well as the capacity to receive signals emitted from severalsensing structures wherein each of the emitted signals have acharacteristic operating range or frequency allowing each to bedistinguished from the other, may be used. This wide-band capability, ofcourse, requires either the use of broadband antennas, such as spiralantennas, or multiple narrowband transmitting and receiving antennas.Inasmuch as this technology is known to those skilled in the art ofantenna theory and design, no further description is deemed necessary.

FIG. 3 shows another embodiment of the invention wherein the sensor unit501 (e.g. sensor array, antenna and transmitter/transceiver) is disposedin the lid 502 of a container 504 such as specimen cup, and wherein theinterrogator 508 comprises a hand-held arrangement which can be broughtin proximity of the sealed container (specimen cup/lid). The dispositionof the sensor unit 501 on the underside of the lid 502 enables thesensor to be supported in a “head space” 504H of the container 504 andthus exposed to vapors (analyte) which has a predetermined relationshipwith a sample 509 sealed within the container 504. It will be noted thatthe sample is illustrated as being a liquid. However, the sample is notso limited and can be solid, semi-solid (e.g., gel/past) or even gas(e.g., a sample of contaminated air, a sample of a person's breath orthe like).

This arrangement permits the sensor unit 501 in the lid 502 to beexposed to the analyte and activated via a wirelessly transmittedinterrogation signal 508S from the interrogator 508 and for the signal501S which is subsequently generated by the sensor unit 501 to bereceived by the interrogator 508.

By permitting the interrogator 508 to be held in relative closeproximity to the sensor unit 501, the power of the interrogation signal508S can be reduced to reduce noise in an environment such as a hospitalwherein pacemakers and/or the like type of sensitive electronicequipment can be affected and/or in situations wherein detection of theinterrogation signal is not desired.

The direction of the interrogation signal 508S can also be limited ingiven embodiments so that, in the event that there are multiple sampleseach disposed in a container and wherein the containers have beencollected together, each of the containers can be interrogatedindividually without cross-talk from those nearby. This arrangementenables the transmitting arrangement which form part of the sensor unitsto be the same and thus reduce both complexity and cost.

This type of arrangement, by way of example, finds application inscreening athletes at a meet for drug use. Each container can take theform of a specimen cup containing a urine sample. By being able toselectively read the output of each of the sensor units 501 disposed inthe lids of the specimen cups, it is possible to screen a plurality ofspecimens within a short period of time. This would be useful, e.g.,testing employees for drug abuse. A similar procedure can be carried outin hospitals wherein screening for diabetes (for example) is beingcarried out.

It is, as shown in FIG. 4, also within the scope of the presentinvention to be able to also collate the output of the sensor unit 501within the container/cup with other data such as patient data and/ordata designed to permit anonymity. By rendering the interrogator 508multi-functional in this manner, it is possible for an embodiment of theinvention to not only wirelessly interrogate a sensor unit 501 for datapertaining to a sample isolated within a container, but also collect andcollate data through such means and the provision of avisible/non-visible bar-code 510 on the container and the inclusion ofbar code reader or the like in the interrogator 508.

It should be appreciated that the size of the container is not limitedto cups and the like and should be taken to include those which providean enclosed head space in which analyte containing vapor can collect,such as cargo containers for aircraft, shipping containers for deliveryby container ship/rail or even rooms. For example, a sensor unit can beused to detect an analyte which is given off by explosives or the liketype of weapon/contraband. By disposing such a sensor or a series ofsuch sensors in the cargo pod, such as used in commercial aircraft, thepresence of materials which have not been detected by other forms ofscreening and which are dangerous, may be rendered detectable andappropriate action taken.

FIG. 5 depicts a situation wherein the interrogator 508 is configured tocollect data in the manner shown in either of FIGS. 3 and 4 and to relaythis data to a host arrangement 512 which can be more distal from theinterrogator 508 than the samples and the sensor unit or units 501.While each interrogator 508 can be capable of analyzing the collecteddata, its size enables it to carry a power supply which would enabletransmissions over relatively large distances and thus provide theability to pass on the collected data to a host such as that located ina tactical command center. This, of course, would enable teams ofinvestigators, each having their own interrogators, to worksimultaneously and separately and wirelessly report sampling data backin manner which would allow the centralized, high speed collation andanalysis of multiple data sets.

While the present invention has been described with reference to only alimited number of embodiments, as will be understood by those of skillin the art, the present invention which relates to an improved chemicalsensing system using a passive chemical sensor unit, may be embodied inother specific forms without departing from the essentialcharacteristics thereof.

For example, the interrogation unit and the sensing unit may communicateover any suitable frequency range, using any suitable one or moreantenna designs. Furthermore, the container may be of any size and madeof any suitable material to hold the sample, or more than one containermay be used with the chemical sensing system described above. Inaddition, the interrogator unit/device need not be portable/handheld andmay take the form of a stationary unit which is provided with a conveyor(for example) to transport the sealed container(s) thereby.

Accordingly, the foregoing disclosure is intended to be illustrative,but not limiting, of the ranges and scopes of the invention, which isset forth in the following claims.

1. A sensor arrangement comprising: a container configured to beenvironmentally sealed and to hold a chemical analyte; an interrogationunit which is separate from the container and operable to wirelesslytransmit an interrogation signal and to wirelessly receive a response; asensor array unit in fluid communication with the analyte disposedwithin the container, the sensor array unit being configured toanalytically respond to a chemical characteristic of the analyte; and aresponder unit connected with the sensor array unit, the responder unitbeing configured to be powered by the interrogation signal, theresponder unit being operable to wirelessly transmit to theinterrogation unit a signal indicative of the sensor array unit'sresponse to the analyte, wherein the container has an upper portion andwherein the sensor array is provided on the upper portion, wherein thesensor array unit comprises a power supply system that includes astorage device configured to store electrical power generated by receiptof the interrogation signal output by the interrogation unit, andwherein the upper portion corresponds to a lid of the container.
 2. Thesensor arrangement of claim 1, wherein the sensor array is supported bythe upper portion.
 3. A sensing method, comprising: closing a containerand enclosing a sensor array therein such that the sensor array isanalytically exposed to vapor from the sample so as to be analyticallyexposed thereto; using an interrogation unit which is separate from thecontainer to wirelessly transmit an interrogation signal to a responderunit operatively connected with the sensor array, wherein theinterrogation signal powers the responder unit; generating a responseindicative of the sample as sensed by the sensor array; wirelesslytransmitting the response to the interrogation unit using the responderunit; and wherein the sensor array is provided on an upper portion ofthe container, wherein the sensor array comprises a power supply systemthat includes a storage device configured to store electrical powergenerated by receipt of the interrogation signal output by theinterrogation unit, wherein the upper portion corresponds to a lid ofthe container.
 4. The method of claim 3, further comprising supportingthe sensor array by the upper portion of the container.
 5. The sensorarrangement of claim 1, wherein the sensor array unit is configured toperform a sensing function even in the absence of the interrogationsignal, by operating under power provided by the storage device of thepower supply system.
 6. The method of claim 3, wherein the sensor arrayis configured to perform a sensing function even in the absence of theinterrogation signal, by operating under power provided by the storagedevice of the power supply system.